Solid Geometry Formulas

Volume and surface area formulas for three-dimensional solids. These are the exact formulas the Calxy volume calculator uses, listed with the measurements each one needs.

Volume and surface area of 3D shapes

Volume is measured in cubic units and surface area in square units. S is the total surface area including any flat bases unless the entry says otherwise.

Solid formulas used by the Calxy volume calculator
SolidInputsFormulas
CubeSideV = s³; S = 6s²
Rectangular prismLength, Width, HeightV = lwh; S = 2(lw + lh + wh)
SphereRadiusV = 4πr³/3; S = 4πr²
HemisphereRadiusV = 2πr³/3; S = 3πr² (including base)
CylinderRadius, HeightV = πr²h; S = 2πr(r+h)
ConeRadius, Perpendicular heightV = πr²h/3; S = πr(r+√(r²+h²))
Conical frustumBottom radius, Top radius, Perpendicular heightV = πh(R²+Rr+r²)/3
Square pyramid frustumBottom base side, Top base side, Perpendicular heightV = h(a² + ab + b²)/3; S = a² + b² + 2(a + b)·s, s = √(h² + ((a − b)/2)²)
Square pyramidBase side, Perpendicular heightV = s²h/3
Rectangular pyramidBase length, Base width, Perpendicular heightV = lwh/3
EllipsoidSemi-axis a, Semi-axis b, Semi-axis cV = 4πabc/3
CapsuleRadius, Straight cylinder lengthV = πr²(h+4r/3); S = 2πr(2r+h)
Hollow cylinderOuter radius, Inner radius, HeightV = π(R²−r²)h
Triangular prism — three triangle sidesTriangle side a, Triangle side b, Triangle side c, Prism lengthEnd area T = √(s(s−a)(s−b)(s−c)); V = T·L; S = 2T + (a + b + c)L
Hollow cylinder — outer radius and wall thicknessOuter radius, Wall thickness, Heightr = R − t; V = π(R² − r²)h
Triangular prismTriangle base, Triangle perpendicular height, Prism lengthV = base × triangle height × length / 2

Sources: OpenStax: Contemporary Mathematics §10.7 Volume and Surface Area

Cavalieri's principle and prism rules

Any prism or cylinder has volume V = (base area) × (height), whatever the shape of its base. Any pyramid or cone with the same base and height has exactly one third of that volume: V = (base area) × h ÷ 3.

Scaling every length of a solid by a factor k multiplies its surface area by k² and its volume by k³.

References

Frequently asked questions

What is the volume of a sphere?

V = 4πr³/3, where r is the radius. Its surface area is S = 4πr².

Why is a cone one third of a cylinder?

A cone with the same base radius and height as a cylinder has exactly one third of its volume, V = πr²h/3. The same one-third rule links every pyramid to the prism with the same base and height.